According to the 1997 U.S. Pet Ownership and Demographics Sourcebook (American Veterinary Medical Association; ISBN: 1882691024), approximately 31.6% of U.S. households have at least one dog and 27.3% of U.S. households have at least one cat. Many of these household pets require access to areas both inside and outside of the home. For example, a dog may spend the bulk of its time indoors, but it typically goes outside for the purposes of urination and defecation. Similarly, many dogs and cats are given the freedom to enter or leave the home at will so that they can have more varied and interesting lives.
Providing a pet access to the inside and outside areas of the household often requires human intervention. Upon notification by the dog or cat that it wishes to enter or leave, the pet owner must open and close a door to allow the pet to pass through. To overcome that problem, the pet owner may provide an access opening (or "doggie door") that is continually open, or capable of being opened at will by the pet, thereby providing the pet with the freedom of access without requiring human intervention. Such access openings, however, have the undesirable consequence of permitting access to the inside of the home to unwanted animals such as other dogs or cats, raccoons, rodents, or even human thieves.
Efforts have been made to address the security problem associated with "doggie doors." For example, U.S. Pat. No. 5,992,096 to De La Cerda et al. discloses a controllable pet access system that utilizes an identifying tag carried on the collar worn by the pet. To keep out undesired animals while permitting access to the pet, the De La Cerda system attempts to detect the identifying tag worn by the pet upon a motion sensor's detection of the animal at the inside or outside of a pet door. The pet door is only unlocked upon receiving a signal from an appropriately coded tag, thereby providing access to only the desired pet or pets. While somewhat effective, the De La Cerda access system suffers from various deficiencies. First, because the identifying tag is carried by the pet's removable collar, the access system is vulnerable to an unauthorized intruder removing the identifying tag from the pet and using it to enter the home. Second, there is no backup detector in case the first detector is insufficient to prevent abuse. Finally, the De La Cerda access system is not configured to couple to the enclosure's security system, which means that an intruder could break through the pet door undetected. This inability to detect unauthorized breaches of the pet door, a vulnerable point in the household's security to begin with, reduces the overall integrity of the household's security.